I shut mine off if I am going to be gone a couple days. I had the T&P open on the water heater (we were home, but outside) and it flooded things pretty good. If we were away, it would have been much worse.
Kill the breaker to the WH too when the water is off. If the water level were to drop below the heater element when the power was on, the element would burn out quickly.
It really only makes sense to turn off water when away for an extended period. If you are worried on a day-to-day basis, there are water detection sensors that can work as an alarm or to control a valve to cut off water if water is detected on the floor.